User`s manual

Troubleshooting Troubleshooting
11 – 6
11.2.2 The MODE LED does not turn on
Refer to the following flowchart when the MODE LED of the CPU module does not turn on at pro-
grammable controller power-on.
The MODE LED has not turned on
POWER LED off:
refer to section 11.2.4
POWER LED on (red) (redundant
power supply modules only):
refer to section 11.2.6
Can MODE
LED turn on?
Can MODE
LED turn on?
Can MODE
LED turn on?
Check the wiring and power on all
the power supply modules.
Connect the extension cable properly
Set the RESET/L.CLR switch to
the neutral position.
Completed
A hardware fault may have occurred in
any of the following modules:
 Main base unit, extension base unit
 Extension cable
 CPU module
 I/O module or intelligent function
module
Perform operations in due order, star-
ting with the minimum system where the
power supply module and CPU module
are mounted on the main base unit.
For the module that does not operate,
please consult your local Mitsubishi ser-
vice center or representative, explaining
a detailed description of the problem.
Is the POWER LED
of the power supply
module green?
Is the extension cable
connected properly?
(OUT -> IN)
Is the CPU module
RESET/L.CLR switch in
the neutral position?
NO
NO
NO
NO
NO
Neutral position
YES
YES
YES
RESET position
YES
YES
YES
Hardware fault of power supply module
Replace the power supply module and
confirm that the "POER" LED is turned on
green.
NO
Can MODE
LED turn on?
YES
NO
YES
Can the CPU
communicate with the program-
ming device?
Carry out PLC diagnostics, and perform
troubleshooting according to the diag-
nostics result.
NO
Connect programming device and CPU module
Are all the power supply
modules powered on? Is the wiring
of the power supply
module correct?